With the advance of the micro-component technology, attention is paid to not only semiconductor devices, but also MEMS devices and micro-equipment having MEMS devices built therein. MEMS devices are constructed as micro-structures on substrates including silicon substrates and glass substrates. In these devices, a driver component for delivering a mechanical drive force, a driving mechanism for driving the driver component, and a semiconductor integrated circuit for controlling the driving mechanism are electrically and mechanically combined.
The characteristic feature of the MEMS device is that the driver component constructed as a mechanical structure is incorporated as part of the device. Driving of the driver component is electrically performed by adapting a Coulomb attraction between electrodes. For example, an optical MEMS device functioning as an optical modulator utilizing the movement of a driver component in the reflection or diffraction of light has been developed as a typical MEMS device.
The MEMS device is manufactured by the micromachining technology, which is generally classified into two categories. One technology is bulk micromachining based on silicon bulk etching. This is the technology of processing a silicon substrate itself to form a three-dimensional structure and becomes the mainstream of the current micromachining technology.
The other technology is surface micromachining. The method involves depositing a sacrificial layer and a thin film on a surface of a silicon substrate from different materials in sequence, patterning the thin film on the outermost surface side into a desired shape, and selectively etching away the sacrificial layer, leaving a structure having a cavity. As examples of implementing the technology, Patent Document 1 discloses a method for manufacturing a pressure sensor; Patent Document 2 discloses a method for manufacturing an inkjet printer head; and Patent Document 3 discloses a method for manufacturing a MEMS device having a hollow layer.